There is a trend towards increasingly large passenger aircraft, for which it is desirable to have correspondingly large wing spans. However, the maximum aircraft span is effectively limited by airport operating rules which govern various clearances required when manoeuvering around the airport (such as the span and/or ground clearance required for gate entry and safe taxiway usage).
To address this problem, various arrangements comprising moveable wing tip devices, that specifically enable the span to be reduced in a ground configuration, have been suggested.
WO2015/150835 is an example of a suggested arrangement. In the arrangement of WO2015/150835 the wing tip device and the fixed wing are separated along an oblique cut plane and the wing tip device is rotatable about an axis of rotation perpendicular to that cut plane.
In the arrangement of WO2015/150835, sealing the interface between the fixed wing and the wing tip device (when the wing tip device is in the flight configuration) has been found to be problematic. More specifically, as the wing tip device rotates between the flight and the ground configurations, relative sliding motion occurs at the interface between the outer end of the fixed wing and the inner end of the wing tip device. Whilst a sliding seal may, in principle, be employed, such a solution is sub-optimal because sliding seals tend to be subjected to relatively large amounts of wear. This may make them susceptible to wear and/or damage and may therefore necessitate frequent inspection and/or replacement of the seal.
Aspects of the present invention seek to address this problem.